The invention relates to a cardiac pacemaker.
Physiologically controlled cardiac pacemakers are known in which the escape interval is regulated by a parameter derived from the body. In this connection, the article entitled "Ein Herzschrittmacher mit belastungsabhangiger Frequenzregulation" [A Cardiac Pacemaker With Stress Dependent Frequency Regulation] in the periodical Biomedizinische Technik [Biomedical Technology], No. 20, 1975, pages 225, 226, describes regulation by means of the respiration rate, while U.S. Pat. No. 4,467,807 discloses a pacemaker in which the base rate is regulated by the oxygen saturation.
Physiological control here means influencing the pacemaker so as to adapt the performance capability of the heart to the momentary requirements, i.e. particularly with respect to its basic rate which is independent of the prior patient specific regulation on the basis of electrical signals derived from the heart that were provided solely to avoid the simultaneous occurrence of stimulated pulses and spontaneous heart action.
Such pacemakers have the drawback that the relationship between the escape interval and the physiological parameter must either be given arbitrarily or the treating physician must adapt it to the individual patient in a time consuming series of experiments.